Radioantibodies to CEA have been found to successfully localize tumors in experimental systems of human tumors in animals and in man. The purpose of this project is to take advantage of this selective tumor localization for more specific radiation therapy, utilizing the principles of neutron capture radioimmunotherapy. This involves the design and synthesis of boron-containing compounds capable of labeling immunoglobulins prepared against carcinoembryonic antigen (CEA) with the retention of immunoreactivity. The boron-labeled immunoglobulins will serve as a means of transporting and localizing boron in colon cancer. Tumor cell destruction will then be accomplished by the well-known ability of 10B to absorb thermal neutrons with production of short-range high-energy particles. This concept and method will be evaluated in the GW-39 colonic cancer system, which is a serially propagated human colon tumor in hamsters. Evaluation of the method will be made on the basis of: (1) concentrations of 10B in the tumors as compared to other host tissues; (2) microdistribution of 10B in tumor; and (3) tumor regression and/or destruction. This study should serve as a basis for possible later clinical trials.